In cargo carrying aircraft it is usual for the cargo to be secured on pallets or other load carriers such as containers which are introduced into the aircraft either through a rear door or a side door and are moved longitudinally of the aircraft into the position which they are to occupy in flight over load carrying rollers.
In some cases cargo may be received within containers, in which case the bottom of the container may be considered as equivalent to a pallet with suitable modification being made to the sides and/or ends of the container to accommodate restraint means. For convenience the cargo carrying structure will usually be referred to herein as a pallet, but it is to be understood that this term encompasses a container.
As the pallet is moved within the aircraft into the position which it is to occupy in flight, it is desirable to provide guide means positioned at the side of the path traversed by the pallet, which furnishes guides for the pallet as it is moved into final position.
While in some cases the pallet may occupy substantially the full width of the cargo carrying space, the present invention is designed for use with pallets which have a width somewhat less than one-half the width of the cargo carrying space or load support surface, and which in flight occupy a position at one side or the other of a longitudinal center line. Where the pallets are in the final loaded position, it is required to provide longitudinal, lateral and vertical restraint. The present invention is concerned with fixtures referred to herein as restraints which are intended to be mounted in a longitudinally extending row along the center line of the aircraft and to constitute abutments serving as lateral guides and restraints as well as vertical restraints preventing upward movement of the loaded pallets as might otherwise occur in flight.
It is desirable that restraints be retractable below the level of the usual load supporting rollers defining the load support surface of the aircraft, so that pallets of different shapes and sizes may move without interference over the restraints in loading and unloading the vehicle. In the past it has been known to provide retractable restraints pivoted about axes extending longitudinally of the aircraft so that they may be manually swung into retracted position. However, such restraints have no provision for yielding when engaged by longitudinally moving pallets, and accordingly, unless retracted, may be broken or damaged when engaged by such longitudinally moving pallet.
In accordance with the present invention, restraints are provided which are pivoted for movement into and out of operating position, or in other words into and out of retracted position, about transversely extending axes so that if in erect or operating position as a pallet is moved into engagement therewith, the restraint is pivoted by the pallet into retracted position and the pallet is permitted to move freely over the restraint.
In accordance with the present invention the restraints include upwardly extending pivoted guides or posts which however are not yieldable laterally and thus are effective to constitute lateral guides for pallets moving along one side or the other of the center line of the aircraft as well as lateral restraints for the pallet in flight.
In addition the restraints include laterally extending vertical restraining arms at the upper or free ends of the post which are adapted to overlie edge portions of the pallet in loaded position and to prevent upward movement of the pallet away from the deck of the cargo space.
Spring means are provided which are effective to perform in different modes according to the particular requirements of the cargo system. In one mode the springs are effective to retain the posts upwardly or in either forwardly or rearwardly retracted position. In a second mode the spring means are effective to retain the posts in upwardly extending position unless positively moved to retracted position, and to return the posts to upright position immediately upon release. Finally in a third mode means are provided to limit pivoting retraction of the post to one direction only so that the post acts as a fixed abutment limiting further movement of a pallet coming into engagement therewith.